Allocated fixed costs, often called common costs, are costs that are not traceable to a particular product, service, product line, or segment. They are never relevant because the costs are assigned to a number of products.llocated fixed costs, often called common costs, are costs that are not traceable to a particular product, service, product line, or segment. They are never relevant because the costs are assigned to a number of products.
Definition of roost. 1  1a : a support on which birds restb : a place where winged animals and especially birds customarily roost. 2  2 : a group of birds roosting together.
roost - a shelter with perches for fowl or other birds. 1  henroost - a roost for hens at night. 2  perch - support consisting of a branch or rod that serves as a resting place (especially for a bird) 3  shelter - protective covering that provides protection from the weather.